Advanced tools in Quality Management
1. General sampling principles
,1.1 Quality control in food production
Quality control is the basic activity of food quality management with the
objective to keep product properties, production processes and human
processes between acceptable tolerances. There are four main control activities:
- Measuring according to specifications set by
- Testing
- Regulating if it is not what it should be
- Taking corrective actions
Control is required to reduce uncertainty and achieve acceptable variation.
Control begins with measuring before, during and after production. Variation is a
characteristic of food because:
- It consists of biological materials
- Production involves human processes
There are different sources of variation:
- Common causes: variation from inherent/natural sources embedded in the
system itself (e.g. inherent variability in incoming materiasl
- Assignable/special/incidental causes: variation arising from external
sources e.g. improperly adjusted machines, operator errors or defective raw
material.
Measuring involves taking and analysing the product to check if quality or safety
parameters are within tolerances
1.2 Sampling defenition and importance
Sampling is taking a fraction of a batch representing the whole batch, meaning
it should mirror the whole batch. This is done because inspecting 100% of the
population is expensive, time consuming and destructive. A sample is a subset
from a large population or process. This subset is a number of units or quantity
of material that is representative of the whole population and mirrors its
characteristics.
,Samling ensures that the sample is similar in variability to the population. This
can be achieved:
- Without statistical basis (Ad hoc)
- With a statistical based plan (acceptance sampling)
In milk supplied in tanker trucks containing compartments, a sample can be
taken from each compartment. However, in some cases, 100% of sampling is
needed, for example when filling boxes with eggs where every box needs the
right amount of eggs. Some materials do not require sampling; when a supplier
has shown to be reliable, it can be possible that the supplier sends a Certificate
of Analysis (CoA), where they have analysed the raw material and internal
analysis is not needed.
1.3 Purpose of sampling
Routine testing/validation: checking quality/safety parameters.
- Incoming material: monitors the quality of incoming materials and examines
the number of defective products in a batch of goods
- In production
- Finished product: gives an indication of the overall performance of the
QMS/FSMS as a result of technological and managerial dependent control
activities that are executed to keep hazards below required limits. Sampling
and analysis to verify conformance before passing goods to consumers.
Verification: to ensure that production runs in a desired manner. Intermittent
samples can be taken during production and control is verified in food safety
management. If unacceptable results are found, corrective actions need to be
taken. It can be used to examine:
- Food safety control systems
- Process performance/capability
- Shelf-life with retention samples (stored samples that can be used for
analysis if there would be a complaint or if shelf life needs to be examined)
The point of control may vary based on the product or parameter of interest.
1.4 Factors in sampling
There are four crucial factors in sampling:
- Location of sampling: provides information about the performance of
production/process control activities. It systematically is identified by the
implementation of HACCP. The HACCP schemes are an ideal layout of the
stages for collecting samples. Using these sampling locations can be
determined. Location depends on:
, o Any critical fault which could develop at that point
o Variability of quality at that point
o Cost of sampling
- How samples should be taken: there can be homogenous sampling where it
is uniform in nature (liquid foods) or heterogenous where it is less uniform
in nature (meat, fish). Large amounts of sampling counteract high variability.
- Sample size: the accurate sample size depends on
o How representative the sample is of the population
o The extent of homogeneity of the food material
o Level of sensitivity of measuring instrument
o Statistical considerations (confidence interval/significance)
Increasing the sample size reduces errors and improves the parameter
analysed, but costs more money and effort.
- Frequency of sampling: refers to the numbers of times samples can be taken
and analysed at sampling locations to establish a trend. It depends on the
production process risk(experience) and on the relationship with the supplier
(trust). Sampling can be based on every batch, and can be done at the start,
intermediate and end of the production. The extent of risk associated with a
product determines the sampling frequency (e.g. viscosity – high variability
but tight specifications needs more frequent sampling). However, resource
considerations need to be made (time, finance, personnel).
1. General sampling principles
,1.1 Quality control in food production
Quality control is the basic activity of food quality management with the
objective to keep product properties, production processes and human
processes between acceptable tolerances. There are four main control activities:
- Measuring according to specifications set by
- Testing
- Regulating if it is not what it should be
- Taking corrective actions
Control is required to reduce uncertainty and achieve acceptable variation.
Control begins with measuring before, during and after production. Variation is a
characteristic of food because:
- It consists of biological materials
- Production involves human processes
There are different sources of variation:
- Common causes: variation from inherent/natural sources embedded in the
system itself (e.g. inherent variability in incoming materiasl
- Assignable/special/incidental causes: variation arising from external
sources e.g. improperly adjusted machines, operator errors or defective raw
material.
Measuring involves taking and analysing the product to check if quality or safety
parameters are within tolerances
1.2 Sampling defenition and importance
Sampling is taking a fraction of a batch representing the whole batch, meaning
it should mirror the whole batch. This is done because inspecting 100% of the
population is expensive, time consuming and destructive. A sample is a subset
from a large population or process. This subset is a number of units or quantity
of material that is representative of the whole population and mirrors its
characteristics.
,Samling ensures that the sample is similar in variability to the population. This
can be achieved:
- Without statistical basis (Ad hoc)
- With a statistical based plan (acceptance sampling)
In milk supplied in tanker trucks containing compartments, a sample can be
taken from each compartment. However, in some cases, 100% of sampling is
needed, for example when filling boxes with eggs where every box needs the
right amount of eggs. Some materials do not require sampling; when a supplier
has shown to be reliable, it can be possible that the supplier sends a Certificate
of Analysis (CoA), where they have analysed the raw material and internal
analysis is not needed.
1.3 Purpose of sampling
Routine testing/validation: checking quality/safety parameters.
- Incoming material: monitors the quality of incoming materials and examines
the number of defective products in a batch of goods
- In production
- Finished product: gives an indication of the overall performance of the
QMS/FSMS as a result of technological and managerial dependent control
activities that are executed to keep hazards below required limits. Sampling
and analysis to verify conformance before passing goods to consumers.
Verification: to ensure that production runs in a desired manner. Intermittent
samples can be taken during production and control is verified in food safety
management. If unacceptable results are found, corrective actions need to be
taken. It can be used to examine:
- Food safety control systems
- Process performance/capability
- Shelf-life with retention samples (stored samples that can be used for
analysis if there would be a complaint or if shelf life needs to be examined)
The point of control may vary based on the product or parameter of interest.
1.4 Factors in sampling
There are four crucial factors in sampling:
- Location of sampling: provides information about the performance of
production/process control activities. It systematically is identified by the
implementation of HACCP. The HACCP schemes are an ideal layout of the
stages for collecting samples. Using these sampling locations can be
determined. Location depends on:
, o Any critical fault which could develop at that point
o Variability of quality at that point
o Cost of sampling
- How samples should be taken: there can be homogenous sampling where it
is uniform in nature (liquid foods) or heterogenous where it is less uniform
in nature (meat, fish). Large amounts of sampling counteract high variability.
- Sample size: the accurate sample size depends on
o How representative the sample is of the population
o The extent of homogeneity of the food material
o Level of sensitivity of measuring instrument
o Statistical considerations (confidence interval/significance)
Increasing the sample size reduces errors and improves the parameter
analysed, but costs more money and effort.
- Frequency of sampling: refers to the numbers of times samples can be taken
and analysed at sampling locations to establish a trend. It depends on the
production process risk(experience) and on the relationship with the supplier
(trust). Sampling can be based on every batch, and can be done at the start,
intermediate and end of the production. The extent of risk associated with a
product determines the sampling frequency (e.g. viscosity – high variability
but tight specifications needs more frequent sampling). However, resource
considerations need to be made (time, finance, personnel).
